Is HIV Evolving to Be Less Deadly?

December 2, 2014

HIV may be evolving to be less deadly, according to a recent study published in the Proceedings of the National Academy of Sciences. However, some caution not to get too excited by recent media coverage of the study.

The study, conducted by researchers at the University of Oxford, compared two cohorts of individuals living with HIV in Botswana and South Africa. In particular, they compared how HIV has adapted to HLA molecules, namely HLA-B*57 and HLA-B*58:01, which protect against disease progression, in the two regions.

"In Botswana, where the epidemic started earlier and reached higher adult seroprevalence than in South Africa, HIV replication capacity is lower. HIV is also better adapted to HLA-B*57, which in Botswana has no protective effect, in contrast to its impact in South Africa," the authors wrote.

The reasoning could be that epidemics in new hosts decrease the virulence of viruses over time, "with natural selection favoring pathogens that cause minimal damage," according to the researchers.

In the case of HIV, this data suggest that the virus's evolution is happening relatively quickly, and over time could reduce the viral replication capacity at the population level.

This process may be accelerated by the increasing role of antiretroviral therapy in people living with HIV. In addition to suppressing viral loads and reducing transmission, the researchers used models to show that ongoing use of antiretroviral therapy may further drive the decline of HIV virulence over the coming decades.

"This is a very compelling study that exemplifies how further research into the mechanism of action of HIV will allow for researchers to eventually eliminate HIV. The study also includes that comprehensive use of antiretroviral therapy also aids in controlling this epidemic by slowly decreasing the virulence of the disease and reducing transmission," Vishal Dahya M.D. from Florida State University College of Medicine told

"This is important for both providers as well as people living with HIV because this is another study that shows that the regulation of this disease is a group effort. The future of HIV research is very bright and much more intriguing research like this study is being done so that we may ultimately subdue this epidemic," Dahya added.

Although the study results have generated significant attention, particularly within mainstream media, not all experts agree that the findings mark a general deterioration of HIV's viral fitness.

"The idea that HIV has become less virulent is based on a small difference in results from a laboratory test that attempts to measure how well the virus replicates, and not any information on the CD4 T cell counts or health of study participants over time," Richard Jefferys of Treatment Action Group told

"A prior research paper found no link between HIV replication capacity measured by this test and the rate of CD4 T cell loss over time, so the lower virus replication capacity reported in the new study may not necessarily be linked to slower disease progression," Jefferys added.

Warren Tong is the research editor for and

Follow Warren on Twitter: @WarrenAtTheBody.

Copyright © 2014 Remedy Health Media, LLC. All rights reserved.

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